ZrO2 aerogels as drugs delivery platforms: Synthesis, cytotoxicity, and diclofenac delivery

This work reports on the synthesis of ZrO2 aerogels by the epoxide-assisted sol-gel method using supercritical drying with CO2, and investigates the influence of HNO3 as a catalyst and cetyl trimethyl ammonium bromide (CTAB) surfactant on the structural, morphological, and textural properties of ZrO2 aerogels. The results indicate that the ZrO2 aerogel prepared without using a catalyst and CTAB surfactant (Zr–0H/0C) had a high surface area (SBET = 275.30 m2 g−1). On the other hand, the use of CTAB surfactant helped to maintain the characteristic 3D network of the aerogel and increase the specific surface area (SBET) by up to 43.40% (Zr-0.1C). The in vitro biocompatibility of the Zr–0H/0C and Zr-0.1C aerogels was evaluated by performing direct hemolysis testing and in vitro cytotoxicity testing using MTT and LDH assays. A murine NIH/3T3 fibroblast cell line was used for these experiments. These results indicate that the ZrO2 aerogels are non-hemolytic and non-cytotoxic. Drug-loading experiments were performed on both ZrO2 aerogels to investigate their drug loading capacity and efficiency using diclofenac sodium (DS) as a model drug. The Zr-0.1C aerogel exhibited the highest efficiency and loading capacity (36.13 and 17.59%, respectively). DS release in simulated bodily fluids (pH 3, 5, and 7) was investigated and the Zr-0.1C aerogel showed sustained release at pH 7.4. In contrast, negligible release was observed at pH 3.0. ZrO2 aerogels are potential biomaterials that can be used as platforms for drug loading and release.